Summary
Linking to PDFs in email marketing, rather than attaching them directly, is a critical best practice for maintaining email deliverability, improving tracking accuracy, and enhancing recipient security. While attachments often trigger spam filters and can lead to a sender's domain being added to an email blacklist or blocklist, providing a link to a hosted PDF (on a landing page or cloud storage) offers a safer and more effective alternative. This approach minimizes the risk of your emails being flagged as suspicious, ensures better analytics on engagement, and provides a more seamless experience for your audience.
Key findings
- Deliverability risk: Direct attachments, especially PDFs, frequently trigger spam filters and can negatively impact your sender reputation, potentially leading to your emails ending up in the spam folder or on a blocklist.
- Improved tracking: Linking to a PDF hosted on a webpage allows for comprehensive tracking of user engagement, including views, downloads, and time spent on the page, which is not possible with direct attachments.
- Security concerns: PDFs can be a conduit for malware and viruses, making mail filters wary of direct attachments and increasing the security risk for recipients.
- Enhanced user experience: Hosting PDFs on a webpage offers flexibility for viewing (directly in the browser or downloaded) and allows for a more controlled user journey, including continued interaction with your brand.
- Avoiding surcharges: Some Email Service Providers (ESPs) may levy additional charges for including attachments, which can be avoided by linking instead.
Key considerations
- Host securely: Always host your PDFs on secure, accessible web pages (preferably using HTTPS) to ensure reliability and trust.
- Optimize landing pages: Design landing pages that not only host the PDF but also provide additional context, related content, and clear calls to action.
- Monitor deliverability: Continuously monitor your email deliverability to ensure your emails with PDF links are reaching the inbox as intended.
- Scan for malware: Before uploading, always scan your PDF files for any potential malware to protect your recipients.
- Consider alternatives: Evaluate whether a PDF is truly the best format. Often, content can be integrated directly into a responsive email or a dedicated webpage, as Mailjet suggests in their article on rethinking PDFs in emails.
What email marketers say
Email marketers consistently advocate for linking to PDFs via dedicated webpages rather than attaching them. Their primary reasons revolve around improved click tracking, enhanced user experience, and the ability to connect recipient engagement with broader marketing analytics, such as cookie tracking. This approach is seen as more efficient and less prone to the deliverability issues associated with direct attachments.
Key opinions
- Prioritize landing pages: The consensus among marketers is to host PDFs on a landing page, offering greater control over content presentation and user interaction.
- Reliable tracking: Website downloads and page views offer more reliable and granular tracking data compared to basic email click rates, allowing marketers to gauge true engagement.
- Cookie integration: Driving traffic to a website connects the user with existing cookies, enabling better personalization and retargeting efforts.
- Content flexibility: Hosting PDFs externally allows marketers to easily update, change, or withdraw the content without having to send a new email.
- Engagement measurement: Tools like click tracking provide detailed insights into how users interact with the linked content.
Key considerations
- Optimize the landing page: Ensure the page hosting the PDF is mobile-friendly, loads quickly, and provides a clear user path.
- Call to action: Clearly indicate that a PDF is linked and what recipients can expect, using strong calls to action (e.g., buttons or clickable images).
- Consider progressive data capture: While sometimes undesirable, a registration wall can be used as an opportunity to collect additional subscriber data.
- Accessibility: Ensure the linked PDF is accessible to all users, including those with disabilities, and that the hosting page provides an optimal viewing experience, as suggested by Mailmodo in their guide on email attachments best practices.
Marketer view
Email marketer from Email Geeks advises that directing recipients to your website through a PDF link helps connect user cookies for better tracking.
Marketer view
Email marketer from Email Geeks highlights that website downloads offer more reliable tracking data compared to simple email click metrics.
What the experts say
Email deliverability experts strongly advise against attaching PDFs directly to marketing emails. Their concerns primarily stem from the significant impact on sender reputation and the heightened risk of emails being classified as spam or malware. PDFs are widely recognized as a major conduit for malicious content, leading to stringent scrutiny by mail filters. This makes direct attachments a risky proposition for any sender focused on maintaining high inbox placement rates.
Key opinions
- Deliverability hazard: Direct PDF attachments frequently trigger spam filters, increasing the likelihood of emails landing in spam folders or being blocked entirely. This directly harms your deliverability.
- Malware vector: PDFs are a notorious vehicle for distributing malware, leading mail filters to be highly suspicious of any email containing them, as highlighted by Awesome Tech Training regarding why sending PDF attachments is a bad idea.
- B2B filter challenges: Interactive PDFs or those containing Personally Identifiable Information (PII) are particularly problematic for business-to-business (B2B) email filters.
- Bounce risk: Large PDF attachments increase the chance of emails bouncing due to recipients' mailbox storage limits.
- Legacy format issues: While older PDF specifications (e.g., 1.4) without interactive capabilities might have historically had better pass rates as attachments, most modern email engines no longer support this by default.
Key considerations
- Always link: The safest and most recommended practice is to always link to a hosted PDF (e.g., on a download page or cloud storage) rather than attaching it.
- Content review: Thoroughly review PDF content for any interactive elements or sensitive data that could trigger filters.
- Blacklist avoidance: Understand the impact of attachments on your sender reputation to avoid landing on an email blacklist (or blocklist).
- Monitor bounce rates: Pay close attention to bounce rates, particularly soft bounces related to mailbox full issues, which can increase with attachments.
Expert view
Email expert from Email Geeks recommends always linking to a download page for PDF content.
Expert view
Email expert from Email Geeks notes that direct PDF downloads often present quirks, particularly for large transactional senders.
What the documentation says
Official documentation and best practice guides from leading email service providers and industry bodies consistently advise against direct PDF attachments in marketing emails. The prevailing recommendation is to link to externally hosted PDFs to circumvent common deliverability pitfalls, enhance security, and enable more robust performance tracking. This guidance underscores the importance of a web-centric approach to content delivery in email campaigns.
Key findings
- Avoid direct attachments: Documentation generally discourages attaching files directly to marketing emails due to the associated deliverability risks and potential for spam flagging.
- Security vulnerabilities: PDFs can pose security risks if not properly handled, emphasizing the need for secure hosting and verification before linking.
- Superior tracking: Web-hosted content, including linked PDFs, allows for detailed analytics that provide insights beyond simple email opens and clicks.
- Improved accessibility: Linking to content generally provides a more consistent and accessible experience for recipients across various devices and email clients.
- File size considerations: Attachments contribute to email size, which can affect loading times and potentially lead to messages being rejected if they exceed mailbox limits.
Key considerations
- Adhere to platform guidelines: Follow specific recommendations from your Email Service Provider or relevant industry bodies for including external content.
- Secure links: Always ensure that linked PDFs are served over HTTPS to encrypt data and build trust.
- Regular content review: Periodically review and update any content linked from your emails to ensure accuracy and continued relevance.
- User expectations: Clearly communicate that a link will lead to a PDF document, managing recipient expectations, as Mailchimp describes in their pros and cons of email attachments.
Technical article
Documentation from Stripo.email advises embedding PDF URLs as hyperlinks and verifying that recipients have proper access to the file.
Technical article
Documentation from Mailjet states that using landing pages built within an ESP is the superior alternative to directly attaching PDF files to emails.
Related resources
15 resources
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